279 lines
6.3 KiB
Python
279 lines
6.3 KiB
Python
"""
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30. Object pagination
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Django provides a framework for paginating a list of objects in a few lines
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of code. This is often useful for dividing search results or long lists of
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objects into easily readable pages.
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In Django 0.96 and earlier, a single ObjectPaginator class implemented this
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functionality. In the Django development version, the behavior is split across
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two classes -- Paginator and Page -- that are more easier to use. The legacy
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ObjectPaginator class is deprecated.
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"""
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from django.db import models
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class Article(models.Model):
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headline = models.CharField(max_length=100, default='Default headline')
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pub_date = models.DateTimeField()
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def __unicode__(self):
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return self.headline
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__test__ = {'API_TESTS':"""
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# Prepare a list of objects for pagination.
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>>> from datetime import datetime
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>>> for x in range(1, 10):
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... a = Article(headline='Article %s' % x, pub_date=datetime(2005, 7, 29))
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... a.save()
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####################################
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# New/current API (Paginator/Page) #
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####################################
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>>> from django.core.paginator import Paginator
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>>> paginator = Paginator(Article.objects.all(), 5)
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>>> paginator.count
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9
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>>> paginator.num_pages
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2
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>>> paginator.page_range
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[1, 2]
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# Get the first page.
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>>> p = paginator.page(1)
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>>> p
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<Page 1 of 2>
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>>> p.object_list
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[<Article: Article 1>, <Article: Article 2>, <Article: Article 3>, <Article: Article 4>, <Article: Article 5>]
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>>> p.has_next()
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True
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>>> p.has_previous()
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False
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>>> p.has_other_pages()
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True
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>>> p.next_page_number()
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2
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>>> p.previous_page_number()
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0
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>>> p.start_index()
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1
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>>> p.end_index()
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5
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# Get the second page.
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>>> p = paginator.page(2)
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>>> p
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<Page 2 of 2>
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>>> p.object_list
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[<Article: Article 6>, <Article: Article 7>, <Article: Article 8>, <Article: Article 9>]
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>>> p.has_next()
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False
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>>> p.has_previous()
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True
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>>> p.has_other_pages()
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True
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>>> p.next_page_number()
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3
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>>> p.previous_page_number()
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1
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>>> p.start_index()
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6
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>>> p.end_index()
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9
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# Empty pages raise EmptyPage.
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>>> paginator.page(0)
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Traceback (most recent call last):
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...
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EmptyPage: ...
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>>> paginator.page(3)
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Traceback (most recent call last):
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...
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EmptyPage: ...
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# Empty paginators with allow_empty_first_page=True.
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>>> paginator = Paginator(Article.objects.filter(id=0), 5, allow_empty_first_page=True)
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>>> paginator.count
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0
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>>> paginator.num_pages
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1
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>>> paginator.page_range
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[1]
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# Empty paginators with allow_empty_first_page=False.
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>>> paginator = Paginator(Article.objects.filter(id=0), 5, allow_empty_first_page=False)
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>>> paginator.count
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0
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>>> paginator.num_pages
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0
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>>> paginator.page_range
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[]
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# Paginators work with regular lists/tuples, too -- not just with QuerySets.
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>>> paginator = Paginator([1, 2, 3, 4, 5, 6, 7, 8, 9], 5)
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>>> paginator.count
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9
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>>> paginator.num_pages
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2
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>>> paginator.page_range
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[1, 2]
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# Get the first page.
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>>> p = paginator.page(1)
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>>> p
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<Page 1 of 2>
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>>> p.object_list
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[1, 2, 3, 4, 5]
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>>> p.has_next()
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True
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>>> p.has_previous()
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False
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>>> p.has_other_pages()
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True
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>>> p.next_page_number()
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2
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>>> p.previous_page_number()
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0
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>>> p.start_index()
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1
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>>> p.end_index()
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5
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# Paginator can be passed other objects with a count() method.
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>>> class CountContainer:
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... def count(self):
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... return 42
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>>> paginator = Paginator(CountContainer(), 10)
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>>> paginator.count
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42
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>>> paginator.num_pages
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5
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>>> paginator.page_range
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[1, 2, 3, 4, 5]
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# Paginator can be passed other objects that implement __len__.
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>>> class LenContainer:
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... def __len__(self):
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... return 42
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>>> paginator = Paginator(LenContainer(), 10)
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>>> paginator.count
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42
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>>> paginator.num_pages
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5
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>>> paginator.page_range
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[1, 2, 3, 4, 5]
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################################
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# Legacy API (ObjectPaginator) #
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################################
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# Don't print out the deprecation warnings during testing.
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>>> from warnings import filterwarnings
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>>> filterwarnings("ignore")
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>>> from django.core.paginator import ObjectPaginator, EmptyPage
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>>> paginator = ObjectPaginator(Article.objects.all(), 5)
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>>> paginator.hits
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9
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>>> paginator.pages
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2
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>>> paginator.page_range
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[1, 2]
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# Get the first page.
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>>> paginator.get_page(0)
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[<Article: Article 1>, <Article: Article 2>, <Article: Article 3>, <Article: Article 4>, <Article: Article 5>]
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>>> paginator.has_next_page(0)
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True
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>>> paginator.has_previous_page(0)
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False
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>>> paginator.first_on_page(0)
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1
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>>> paginator.last_on_page(0)
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5
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# Get the second page.
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>>> paginator.get_page(1)
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[<Article: Article 6>, <Article: Article 7>, <Article: Article 8>, <Article: Article 9>]
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>>> paginator.has_next_page(1)
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False
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>>> paginator.has_previous_page(1)
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True
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>>> paginator.first_on_page(1)
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6
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>>> paginator.last_on_page(1)
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9
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# Invalid pages raise EmptyPage.
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>>> paginator.get_page(-1)
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Traceback (most recent call last):
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...
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EmptyPage: ...
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>>> paginator.get_page(2)
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Traceback (most recent call last):
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...
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EmptyPage: ...
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# Empty paginators with allow_empty_first_page=True.
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>>> paginator = ObjectPaginator(Article.objects.filter(id=0), 5)
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>>> paginator.count
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0
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>>> paginator.num_pages
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1
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>>> paginator.page_range
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[1]
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# ObjectPaginator can be passed lists too.
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>>> paginator = ObjectPaginator([1, 2, 3], 5)
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>>> paginator.hits
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3
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>>> paginator.pages
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1
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>>> paginator.page_range
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[1]
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# ObjectPaginator can be passed other objects without a count() method.
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>>> class Container:
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... def __len__(self):
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... return 42
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>>> paginator = ObjectPaginator(Container(), 10)
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>>> paginator.hits
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42
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>>> paginator.pages
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5
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>>> paginator.page_range
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[1, 2, 3, 4, 5]
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##################
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# Orphan support #
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##################
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# Add a few more records to test out the orphans feature.
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>>> for x in range(10, 13):
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... Article(headline="Article %s" % x, pub_date=datetime(2006, 10, 6)).save()
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# With orphans set to 3 and 10 items per page, we should get all 12 items on a single page.
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>>> paginator = Paginator(Article.objects.all(), 10, orphans=3)
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>>> paginator.num_pages
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1
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# With orphans only set to 1, we should get two pages.
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>>> paginator = ObjectPaginator(Article.objects.all(), 10, orphans=1)
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>>> paginator.num_pages
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2
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# LEGACY: With orphans set to 3 and 10 items per page, we should get all 12 items on a single page.
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>>> paginator = ObjectPaginator(Article.objects.all(), 10, orphans=3)
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>>> paginator.pages
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1
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# LEGACY: With orphans only set to 1, we should get two pages.
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>>> paginator = ObjectPaginator(Article.objects.all(), 10, orphans=1)
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>>> paginator.pages
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2
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"""}
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